In general, a protection cap for a bolt and a nut is a bolt and nut interception member inserted into bolt and nut portions to prevent the bolt and the nut from oxidizing and to improve a stiff atmosphere of the bolt and the nut.
Such a conventional dual protection cap for a bolt and a nut is generally formed in a cap shape having opened one side that covers and protects an outer protruded portion of a bolt and a nut formed to fasten and fix a base plate that supports a structure such as a streetlight or a soundproof wall to the ground.
More specifically, a conventional protection cap for a bolt and a nut is an interception member for covering and protecting a bolt, a nut, and a washer using a plastic material or a rubber material so as to prevent a bolt and a nut from being wet and rusted due to rain and wind, and a screw thread is formed to couple the bolt and the nut at an inner circumferential surface of a cap main body, and thus the conventional protection cap is generally fixed through bolt and screw coupling.
However, because the above-described conventional protection cap for a bolt and a nut is generally made of a plastic material or a rubber material, when an organic chemical material is exposed at sunlight in view of a characteristic of a plastic or rubber material, an organic chemical component is volatilized to be stiffly hardened and deteriorated and thus there is a problem that the conventional protection cap is easily damaged by an external pressure.
Particularly, when a temperature rises in a summer season, if a bolt and a nut, which are a metal component expand by a heat, in a state in which a protection cap having different expansion coefficients is deteriorated and hardened, there is a problem that the protection cap does not withstand expansion of the bolt and the nut and is damaged.
As described above, when a protection cap for a bolt and a nut is damaged, the protection cap loses a function of maintaining airtightness from the outside, and thus there is a problem that the bolt and the nut are oxidized by rainwater or moisture.